Hadrorhyparus vitiensis Skelley & Minkina, 2025

Skelley, Paul E. & Minkina, Łukasz, 2025, Review of the Rhyparini (Coleoptera: Scarabaeidae: Aphodiinae) of eastern Melanesia and Polynesia, with descriptions of new species, Zootaxa 5632 (1), pp. 115-137 : 125-127

Hadrorhyparus vitiensis Skelley & Minkina , new species

Figures 23–27

Diagnosis. Hadrorhyparus vitiensis is recognized by the more parallel-sided body (when compared with other species in the genus), length 3.4 mm ( Figs. 23–25 ). Pronotal lateral margin explanate and weakly sinuate, nearly straight, without sharply defined anterior and median lobes; submarginal costa straight posteriorly reaching sharp posterior angle. Elytron with dorsal intercostal surfaces medially smooth, glabrous and glossy, long setae only near costae; submarginal costa distinct posteriorly, distinctly curving upward into distinct caudal bulb; trichome present ( Fig. 27 ). Metaventrite long, distance between mesocoxa and metacoxa nearly equal to width (long axis) of metacoxal; median groove evident as deep longitudinal groove. Metafemur with posterior margin straight, with weak posterior surface visible only medially ( Fig. 26 ). Metatibia enlarged, dorsal (posterior margin) with large median notch with large basal and apical lobes.

Description. Holotype male. Body length 3.4 mm, width 1.3 mm; generally elongate, tapering posteriorly; dorsally glossy, ventrally weakly glossy; color red-brown. Head. Surface dulled, covered by rather regularly spaced, coarse punctures bearing short setae. Clypeus anterior margin gently, widely rounded to shallow emargination before gena, lateral angles indistinct; anterior margin lacking medial setal fringe; gena gently rounded, weakly protruding. Clypeocentral disc distinctly convex, ringed by a strong peridiscal impression, with weakly evident pair of anteriorly convergent costae. Frons with four weak longitudinal costae. Prothorax. Pronotum shiny, with six distinct convex costae and seven longitudinal intercostae, and prominent lateral margin. All costae on each side with row of minute punctures bearing short, fine setae. Paramedian costa reduced in anterior third, but not interrupted; converging anteriorly. Discolateral costae interrupted near middle. Submarginal costa reduced in anterior third, but not interrupted; straight, continuous sharply angled posterior lateral angle. Median intercostal (between paramedian costa) coarsely punctate, fewer punctures posteriorly. Other intercostae with two rows of coarse punctures anteriorly, lacking punctures and glossy posteriorly. Lateral margin sinuate; anterior and medial lobes weakly distinguished by shallow emargination, similarly weakly rounded; pronotum widest at anterior lobe. Elytron. Each elytron with six elevated costae (including lateral margin) and five flat intervals. All costae on each side with row of minute punctures bearing short, fine setae. Discomedian costa straight, similar development to slight caudal swelling (postdiscal bulb), which has patch of short setae, swollen end projects posteriorly to cover part of caudal bulb. Discolateral costa straight, similar development but gradually reducing in size to caudal end; costa with a small patch of short setae at apex, not apically swollen. Posthumeral costa prominent basally, reducing to fine carina at middle; fine carina continues to apex. Submarginal costa straight, evenly developed to apex, where it turns upward into caudal bulb. Caudal bulb almost circular in dorsal view, vertically elongate in caudal view; projecting to nearly reach apex of discomedian costa; with distinct trichome present between caudal bulb and discomedian costa. All elytral intervals medially flattened, highly glossy, lacking punctures; each side of intervals are rows of small setal bearing punctures. Venter ( Fig. 24 ) moderately shiny, with microreticulation. Prosternal process well developed, posteriorly hastate. Mesoventrite with evenly distributed coarse puncture. Metaventrite flattened in middle, surface with evenly distributed coarse punctures bearing short setae, with distinct shallow median longitudinal groove; sides of median impression with flattened surface and rows of small punctures; anterolateral juxtacostal impression small, groove like; length between mesocoxa and metacoxa nearly equal with width of metacoxae. Abdomen. Abdominal ventrites shiny, with weak microreticulation, with single transverse row of fine punctures, laterally with small depression; ventrites 2–3 very short, ventrite 4 longer, not a long as ventrite 5, ventrites 4–5 appear to be fused, surface of ventrite 5 with evenly distributed coarse punctures bearing fine setae. Pygidium in middle with weak Y-shaped ridge separating transverse depression on each side. Profemur ventral surface with large, dense, welldefined puncture bearing short setae. Legs. Protibia narrow with three small apical teeth. Mesofemur ventral surface with large, dense, weakly-defined puncture bearing short setae; posterior face broad, distinct from base to apex. Mesotibia somewhat flattened, triangular, expanding to broad flattened apex; distinct inner apical spur projecting in same axis with tibia, length almost equal to apical tibial width. Metafemur ventral surface with large, dense, weakly-defined puncture bearing short setae; elongate, swollen at apical third; posterior margin straight, with posterior face present only medially. Metatibia greatly enlarged; inner surface smooth, strongly concave; ventral (anterior) margin evenly curved, broad; dorsal (posterior) margin strongly sinuate, with large median notch separating large basal and apical lobes; outer surface with evenly scattered coarse punctures bearing fine setae, punctures become less distinct on apical half; apex broadly truncate and flattened. Male genitalia. Aedeagus was not dissected from holotype.

Variation. Only the holotype male is known. Females are expected to have the mesotibial spur smaller than the male.

Distribution. Fiji ( Viti Levu).

Material examined. The holotype male ( USNM): “ Nadarivatu, / Viti Levu, Fiji / W. M. Mann // [handwritten] with Triglyphothrix pacificum Mann. // Collection / W M Mann // [cursive handwriting in red ink] Aphodiinae / allied to Termi. / todius Wasm.? / (Krit. Verz. 1894) [referring to the publication describing Termitodius Wasmann, 1894 ] // [red paper] HOLOTYPE ♂ / Hadrorhyparus / vitiensis / Skelley & Minkina”. There is no date of collection on the specimen, but W.M. Mann was a Sheldon Traveling Fellow of Harvard University (Cambridge, Massachusetts, United States of America) in 1915–1916, collecting insects that lived with ants in Fiji ( Mann 1921) .

Etymology. Toponymic.According to historians (e.g., Schultz 1974), Fiji, is a spelling based on the pronunciation of island name by residents of Tonga. However, the indigenous people of “ Fiji ” call the islands, Viti, as in Viti Levu. We honor their name for the islands and name this species, “ viti -ensis ”, meaning “from Viti ”, and by extension “from Fiji ”.

Comments.The holotype of this species was collected with“ Triglyphothrix pacifica Mann, 1921 ” ( Hymenoptera : Formicidae ), which now goes by the name Tetramorium manni Bolton, 1985. The genus Tetramorium Mayr, 1855 , is reported to be mostly predatory, but can live in cavities in logs, twigs, or in the soil. Such habitats are also occupied by termites, which might have been prey for the ant. Present information indicates Termitodiellus and possibly other genera are associated with termites. However, enlarged metatibiae are seen in some ant associated Histeridae (e. g., Terapus Marseul, 1863 ). These tibial modifications may be benefits that allow them to live with ant hosts. Since most rhyparine habits and hosts are unknown, different taxa may associate with differing social insects. Field work and appropriate observations will confirm if the hosts are ants or termites, or potentially both.

Figures

FIGURES 23–27. Hadrorhyparus vitiensis Skelley & Minkina, new species, holotype male (USNM). 23) Habitus, dorsal view; 24) habitus, ventral view; 25) habitus, lateral view; 26) metathoracic legs, oblique-ventral view; 27) elytra and metathoracic legs, oblique-dorsal view. Scale lines = 1.0 mm.